The present application relates to low-voltage power supplies and, more particularly, to a novel line-frequency power supply for energizing a low-voltage load.
It is often desirable to operate a low-voltage load from a relatively higher voltage A.C. source. In particular, there exists a class of low-voltage lamps having an improved efficacy due to operation of the lamp filament at a lower voltage than has been traditionally used for lamp operation. Many circuits for providing such operation either exhibit undesirably high levels of electromagnetic interference or require components having relatively high current and/or voltage ratings. In particular, previous attempts at providing low voltage power sources for incandescent lamps have utilized magnetic components for voltage transformation purposes. The cost of such magnetic components has prevented the resulting power supplies from being economical. Other power supplies have utilized phase-control waveforms, in which very narrow pulses are required, with high surge currents being provided across the load; reliability is frequently reduced in this manner. It is therefore highly desirable to provide a power supply for a low-voltage incandescent lamp and the like load, having relatively low cost, high reliability and in which components of relatively small current rating can be utilized.